FIGS. 1, 2 and 3 are perspective views illustrating a sag phenomenon (a phenomenon in which a driving voltage is changed to an operational environment due to inconsistent operational scope) acting on a configuration of a micro-electromechanical (MEMS) actuator mounted camera module according to prior art.
As illustrated in FIG. 1, a shutter device (120), a micro-electromechanical (MEMS) actuator (100) mounted inside the shutter device (120) and a lens (110) respectively face a horizontal shooting (photographing) direction. Furthermore, a lens moving force (F1) that acts on the lens (110) faces the same horizontal shooting direction, which is perpendicular to gravity (G1), as shown in FIG. 1.
However, as depicted in FIGS. 2 and 3, in case a lens moving force (F2) is opposite to the gravity (G2) (FIG. 2, facing up) and a lens moving force (F3) is in the same direction with gravity (G3) (FIG. 3, facing down), it could be said that an operational scope of the MEMS actuator for realizing a same focal distance cannot be as shown in FIG. 1.
The sag phenomenon occurs due to influence by gravity caused by the shooting direction even in the unlikely event of extreme directions as shown in FIGS. 2 and 3, whereby an operational scope of the lens (110) positioned at an upper surface of the MEMS actuator (100) cannot be constantly guaranteed.
Despite the probability of accurate position adjustment of the MEMS actuator (100), there is a high chance of a large error in focal distance being developed if the sag phenomenon is generated, whereby reliability on auto-focusing (AF) algorithm of a camera module disadvantageously deteriorates.
Thus, there is a need of a new type of a camera module capable of constantly controlling a lens (110) displacement move (drive) by compensating the sag phenomenon even if the shooting directions of the camera module variably change.